Hot Transformer Chassis?
I have seen this done before and it seems to be rather common on old tube gear and TV's. For example, I have a V-M 1465-2 Tuner that I refurbished.
It has a 470k 1/2 watt resistor on the primary side of the power supply transformer that goes to ground. Naturally, with a non-polarized plug it can have full A/C potential or less depending on how it's plugged in. Either way, you've still got A/C on the chassis!
What is it's purpose? And what's the best approach to safely deal with it?
And as noted, there are no isolated grounds and one side of the tube filaments are grounded. Just your standard circuitry, nothing unusual.